You currently have a problem with the RSS Feed function that is going to confuse a lot of people. Let's say I add a feed that WBB doesn't recognise as being a 'valid XML feed'. Rather than the input box reject the feed, instead it still accepts the feed but when run the feed won't work. Furthermore, it will also create an error log in "wcf/log" folder.
That is not something people are going to be aware off, instead left wondering why the feed doesn't work and even why they got a error log file created. Most will not know what caused the error log, or why the feed isn't working if accepted as a valid XML link and not rejected by the field box